Macroscopic osseous changes in the temporomandibular joint related to dental attrition in Japanese macaque skull.

The purpose of this study was to investigate the relationship between osseous changes in the temporomandibular joint (TMJ) and dental attrition in the Japanese macaque. One hundred and thirty Japanese macaque skulls (54 male and 76 female) from animals which had been bred in the same environment, were randomly sampled from a collection at the Primate Research Institute of Kyoto University. The age at death had been recorded in all cases. TMJ osseous changes were independently evaluated by three examiners, and were defined as an irregular surface or a perforated compact bone layer with a markedly irregular surface on either the temporal or condylar components. Age was a significant factor in predicting TMJ osseous changes (P < 0.001). A strong relation was observed between age and dental attrition (P < 0.001), while dental attrition was not a significant factor in predicting TMJ osseous changes (P = 0.334). The prevalence TMJ osseous changes in male animals was slightly higher than in females (P = 0.057). The results of this study suggest that osseous changes in the macaque TMJ are mainly related to age, not to dental attrition.